noun A thick cloud of tiny water droplets suspended in the atmosphere at or near the earth's surface which obscures or restricts visibility (to a greater extent than mist; strictly, reducing visibility to below 1 km) (the collision occurred in thick fog) A state or cause of perplexity or confusion. (the coffee helped clear the fog in my brain)
verb (with reference to a glass surface) cover or become covered with steam. (hot steam drifted about her, fogging up the window) Bewilder or puzzle. (she stared at him, confusion fogging her brain) Spray with an insecticide.
noun The grass which grows in a field after a crop of hay has been taken. (If the humidity is too high, the fog just grows and grows out of control.)